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West Refuse Pile Haul Road: Based on the four test holes advanced along this road, it appears that the • pit run sands and gravels are highly vaziable in depth and condition. The pit run gravels placed in the eastern end of the roadway and above the hill ranged from 12 [0 24 inches in thickness, however, the upper 6 to 8 inches of material were very loose and should be recompacted. A 6-inch layer of pit run sands and gravels was encountered at the roadway surface at the bottom of the hill, however, it was underlain by approximately 22 inches of coal fill material. We did not encounter any pit mn sands and gravels in the western end of the roadway. Based on the conditions encountered along this roadway, we recommend that the western half of the roadway, from the top of the hill to the west end, be constructed with a gravel section consisting of 4 inches of base course gravels and 17 inches of pit run sands and gravels. Prior to placing the pit run sands and gravels, the exposed subgrade soils should be scazified to a minimum depth of 12 inches, brought to within 2 percent of the optimum moisture content determined in accordance with ASTM D698 and then be recompacted to at least 95% of the maximum standazd Proctor density. For the portion of the roadway situated at the east end of the alignment and above the top of the hill, we recommend that the exposed pit run sands and gravels be scazified to a minimum depth of 6 inches and then be recompacted to at least 95% of the maximum modified Proctor density. After this area has been recompacted and tested, an additional 5 inches of pit run sands and gravels should be placed over these materials. Four inches of Class Vi base course gravels should be placed over the pit run sands and gravels after [hey have been adequa[ely compacted. • Horizontal and vertical profiles were not provided for this roadway. Therefore, we did not address these issues in this report. Subbase/Base Coarse Preparation: We recommend that the existing roadways, Haul Road B Extension and Fish Creek Borehole Access Road, be proofrolled with a heavily loaded truck prior [o any gravel placement. Areas which deform excessively under the wheel loads should be removed and stabilized. Areas appearing [o be stable should be scarified to a depth of 4 inches, moistened to the optimum moisture content and then recompacted to at least 95% of the maximum modified Proctor density, in accordance with ASTM D1557. Any additional base course or pit run gravels placed on the roadway or any portions of the roadway where additional gravels are required, should also be compacted to at least 95% of the maximum modified Proctor density at or near the optimum moisture content. The base course and subbase gravels should be approved by the soils engineer, prior to placement. We recommend that the road base gravels placed on the roadways meet the requirements for Class V or VI base course in accordance with the Colorado Department of Transportation specifications. In addition, the subbase gravels should meet [he requirements for Class I or Class II base course. Drainaee: As previously stated, the collection and diversion of surface drainage away from the roadway areas is extremely impottant for satisfactory performance of [he roadway. The design of surface drainage features should be carefully considered to remove all water from all roadway areas. In addition, the maintenance of all drainage structures should be conducted periodically [o ensure proper performance. We recommend that [he new gravel surface be constructed with a crown or super elevation of at least 2 • percent. We also recommend that the existing gravels be reshaped so that a crown is established throughout the pavemen[ section. Job No. 994004 Northwest Colorado Consulunts, Inc. Page 5